Square Split-Ring Resonator as a Sensor for Detection of Nanoparticles in PVDF-Based Nanocomposites at Ultra-High Frequencies: MXenes and MoS2 Concentrations

The performance of a printed square split-ring resonator as a sensor for quantifying nanoparticle concentrations in PVDF-based nanocomposites was evaluated at UHF frequencies. The sensing mechanism was based on the frequency response of parameter S21, observing the shift in the resonant frequency and a variation in S21 level, while samples were placed on the ring split and compared to the sensor without a sample. Experiments with samples of PVDF-based nanocomposites combined with different concentrations of both MoS2 and MXenes, ranging from 0.01% to 0.2%, were conducted. In general, considering both types of samples studied, it was observed that, as the concentration increases, S21 (dB) increases from −6.35 to −6 dB. At the same time, the resonance frequency in the S21 plot went from 500.4 to 498.25 MHz. Although the concentrations and their variations were relatively low, shifts in the resonance frequency of S21 were evident, demonstrating the ability of the sensor to detect low concentrations and variations of MoS2 and MXenes, being the detection of samples with higher concentrations feasible as future work, and concluding that the sensor had a relatively acceptable performance. In this study, MXenes were the concentrations that produced more noticeable shifts in the resonance frequency of S21. Likewise, characterizations based on SEM and TEM were performed to corroborate the ones at UHF frequencies.